Method of distilling coal



July 1,2 1927.

*R. G. GRlswQLD METHOD-OF DISTILLING COAL Sheets-Sheet l Filed April 29. 1922 July 12, 1927.'v

R. G. GRISWOLD I MTHOD OF rDESTILLING COAL 2 Sheets-Sheet 2 Filed April 29. 1922 www@ l phenes.

CII

Patented July l2, `1927.

muren STATES PATENTfoFFIcE.

ROBERT G'. GRISWOLD, OF .WESTFIELD, NEW'JERSEY, ASSIGNOR TO DOHERTY RE- SEARCH COMPANY, OF NEW YORK, N. Y., A CORI.0I|R..A'.lll.'O1\T- OIE' DELAWARE.

METHOD OF DISTILLING COALJ Application filed April 29,

This invention relates to a method of distilling coal and more particularly to a method whereby a high sulphur coal or a coal oi inferior grade may be utilized to produce a coke suitable tor metallurgical purposes: and also whereby a gas maybe obtainedwhich is sufficiently low in sulphur to be suitable for heating and other commercial purposes, and which is below the maximum sulphur content-of gas as prescrib'ed by law. Heretofore high sulphur coals or coals of interior grade have not been utilized for the production otmetallurgical coke for the rea son that no economical commercial process has been known by which the lexcessive sulphur present in the coal could be removed. In the production of gas from such coals it Was observed and shown by experiment that in the distillation of coal to produce a coke therefrom' approximately 60% of the sulphur content remained in the cokeafter distillation and 40% of the sulphur content was found to be lpresent in the gas distilled therefrom. An analysis of the sulphur compounds in the gas produced in this Way` showed that approximately 95% of the sulphur content was present in the form of hydrogen sulphide, and the remainder of the sulphur was present as carbon disulphid and other sulphur compounds such as the thio- Hereafter the latter sulphur com. pounds will be referred to merely as carbonsulphur compounds. 4

Many attempts have been made to develop a practical commercial method of reducing the sulphur content of the coke, as for instance, by passing nitrogen, carbon dioxide and other inert gases therethrough at a high temperature. It has been shown that although the sulphur content is substantially decreased by this means, the high cost of heating the coke and th-e cost of production of the gas to be employed, has rendered the i processes substantially prohibitive. The use of superheated steam has also been experimented with to reduce the sulphur content of the coke, and although a substantial reduction is accomplished by this means, the

. high temperature Which is necessary for the sulphur removal results in a number ofthe side reactions taking place, such as the Water gas reaction, which are undesirable in the coke purification process.

According to the process which I have de- 1922. SerialNo. 557,464.

when the sulphur content of the same is rei duced to the 'maximum desired value, Will be suitable for metallurgical purposes. This I propose to accomplish by purifying the gas distilled from the coal to remove hydrooxide puriiiers and passing the purified as through the bed ot mcandescent fuel. he partially purified gas Will still contain an objectionable amount of carbon-sulphur compounds which are not removed by the oxide purifiers, and which Will be decomposed by passing the gas through the coke chambers in which the distillation of the coal is taking place. In passing the gas through the coke the sulphur content of the coke will also be reduced substantially in accordance with.` the distribution ratio of the sulphur between coke and gas, as set forth above. The gas after a second purication by passage through oxide urfiers may be returned repeatedly througli the coke until the sulphur content thereot has been reduced to the maximum allowable limit. With some coals of fairly lovv sulphur content a single Idistillation and purification. of gas with a return only of. a portion of the gas so distilled through the -coke bed Will be sufficient to render thesulphur content of bot-h the coke and the gas below the maximum allowable limits.

It is the primary object of the present invention to provide a method Whereby'high sulphur coals` or inferior coals Which have heretofore been useless for metallurgical coke production, may be utilized to produce a hard metallurgical coke Whose. sulphur content is Within the maximum allowable limits.l

Another object of the invention is to provide a process whereby a gas of the required standard of purity ,may be economically produced from a high sulphur or inferior grade of coal.

` A further object of the invention is to provide a process in which the Doherty shaft furnace maybe utilied for the economical production jofgasand simultaneous producticp of a yaluable high grade metallurgical co e..

gen sulphide therefrom in the ordinary .i

loo

With these and other` objects in view the invention consists in the method of making as and cokelierena'l'ter described and dened in the claims.

The various features of the invention are illustrated in the accompanying drawings in which the preferred method of distilling coal may be carried out.

Fig. 1 is a diagrammatical view of the4 `portion of the heat regenerators connected therewith.

In the operation of the apparatus an' may be supplied b a blower 1 0 through pipe 12 either' to the ottoni of a regenerator tower 16 through pipe 14; as shown in Fig. l, or to the top of the regenerator through a pipe From thence 4it passes into the main chamber 17 of the regenerator system, which is filled with checker brick. In the passage throu h the regeneratorV the 'air becomes heate to a high temperature and 'then passes upwardly through a regenerator tower 20 from `which it is led to the middle orlower portion of a shaft furnace 22 through a ipe 24. The fuel which is'sup lied to the s iaft furnace, generally a high su phur coal, passes downwardly through the furnace and flows over a supporting member 26, near the lower end of the furnace. The fuel gradually works downwardly and is discharged into a ho per 28, having aV discharge door 30 at the coke is supplied to the ap aratus througha hopper 32 leading into t e .top portion of the shaft furnace and is gradually heated in its passage through the furnace as it progrosses toward a heatzone in the middle or lower portion of the furnace. Theair from the' blower 10 passes through the fuel bed in the zone adjacent to the inlet pipe or nozzle 2iand the waste gases leave the furnace through an opening 34 similar to 24 and pass into a regenerator tower 36 similar to tower 20. From the regenerator 36 the waste gases pass through the heat regenrators 37 and 38 similar to regenerators 17 and 1G re speetively previously,T describeththe complete arrangement being clearly shown in Fig. 2. The waste gases after passing through the regenerator 38 are discharged into the atmosphere through a pipe 40, having a valve 42 therein. In the passage of the air through the fuel bed the ordinary reaction with the carbon talles place in which carbon dioxide is first formed which is then reduced to carbon monoxide by the incandescent' carbon ower Vend thereof. Goal mixed with" ary combustion takes place in regcnerators l 36, v37 and BSfbyywhichf heat is liberated which further` assists, in the heating of the `regenerator system. `By this blowing operation a hot zone in the coke or fuel is formed adjacent the nozzles 2li and `34. which has a temperature in the neighborhood of 2500o F.,

and is suitable for carrying on the water gas eol reaction. At this point of the process the air passing through the regenerators to the @shaft furnace is cut ofi' and steam is passed through the fuel bed in order `to 'generate water gas. This steam is obtained by` passage of water through a pipe (lr6 into s, spray nozzle 48 located below the supporting member 26 in the shaft furnace. TheUY water sprayed into thej fuel hed through thenozzle 48 serves a double purpose e. gQitquenches the coke in the"hottom ofA the shaftand the steamgenerated by the-quenchingaction acts as a medium-.whereby the heatfrecovered from thereoke Ais returned to `the` hot zone of the fuel"columnY and thefsteam then decomi posed intojwaterlgae. The water` is vaporizedfand lsuperlieatedby lissage in contact "wthlthe hot'cokeatfthe 'ottom of the furnace and paesliipwardl 'through the fuel bed into contact-.withft e heated zone4 in whichthewatergasl reaction will take place in the wellknown manner producing hydrogen and carbonA monoxide. The main body ofsteaxnfor the water gas reaction is obtained luy-introducing water through a pipe 50 at the top of the regenerator 88 directly into contact with the preheated checker brick andcthen superheatin thev steam produced by passing it througi the regenerators 37 and 36.l This steam enters the hot zone through the nozzle 34 and then passes upwardly through the fuel bed together with the steam and gas passing upwardly from the bottom of the furnace. The hot gas passing upwardly from the hot zone acts to ,distil off the volatile portion of the coal and this gas mixture leaves the top of the furnace through a pipe 52 and passes to a washer cooler 54. The washer cooler 5ft serves to remove tar and ammonia from the gas and also to reduce the temperature thereof. From the washer cooler the gas passes through pipe 5G having a valve 57-into an ammonia scrubber 58 in which substantially the last traces of ammonia are removed from the gas in lthe woll known manner. From the ammonia scrubber the gas passes through pipe G0 into the ordinary oxide purifiers 62 which serve to remove hydrogen sulphide from the gas but do' not remove carbonsulphur compounds. From the purifiers the'4 gases are led through a pipe 64 into a gas holder 66 which may be of any -desired capacity. After the completion ofthe water gas'inaking operation, the blowing operation is repeated but the gases are'circulated in a direction the reverse of the precedingr blowing operation. .For example air from blower 10 passes through a pipev 67 into regenerator- 88 then through regenerators 37 and 36 to the furnace. The exhaustv gases are burned in regenerator 2() pass through regenerators 17 and 16 to an outlet 69 having a `Valve 71. The water for making steam for the gas making operation is then admitted through a pipe at the top of the regenerator 16.

Coke is mixed with the fuel charged into the furnace only in suliicient quantity to maintain the column of fuel in the shaft in a free and open condition so that the blast air and hot gas currents may easily penetrate to all portions of the charge. The shaft furnace shown in Fig. 1 is so operated that the air for supporting combustion is restricted during its passage through'the fuel column to a comparatively narrow zone lying between the nostrils 24 and 34 f and it is only in this limited Zone that fuel is consumed and temperatures are sufficiently high to support the water gas reaction and to secure a complete decomposition of the carbon-sulfur compounds in the purifying gas circuit. Moreover it is in this limited high tempeiature zone that the coke products of carbonization can be freed from sulfur impurities by the: purifying gases. In the comparatively large section of the furnace above the nostrils 24 and 34 the mixture of high sulfur coalfand coke is gradually heated and the coal is carbonized by heat carried by a current of gas generated in the restricted hot Zone.- The coke produced in this carbonizing zone is very ard and dense because of the-fact that it is formed slowly at a comparatively low temperature and because the coal in they lower portion of the carboniz'ing .zone is subjected to the pressure of a great weight of fuel above it during the critical period when it is undergoingv a final transformation.-

In order to comple-te the purification of the gas and also to-reduce the sulphur content of the coke resulting from thedistilla tion ofthe high sulphur coals, during the gas making operation, thegas may be. re-' turned from, the gas holder through a pipe 68 through a booster or gas pump 70 into a pipe 72 from which the gas may be passed either directly into the lower portion of the shaft furnace through a pipe 74 having a I valve 76 therein, or it may be passed through a pipe 78, having a valve 81, into the upper portion of the regenerator16 through Vwhich the air during the preceding operation was preheated. The choice of the oint at which to pass the gas freed of ydrogen sulphide dependsupon the temperature andl equilibrium conditions of the apparatus, and

the proper pipe through which to pass the gas during the operation will be apparent to an operator familiar with the gas making process. If the gas is passed through pipe 78 into the top of the regenerator 16, water may be passed through'a pipe` 80 having the gas and water will then pass together through the checker brick in the regenerator. The steam produced and superheated in the .regenerator passes together with the 47K5 `valve 82 and spray head 84, into the gas and y sov turned are broken down, forming approximately 95% of hydrogen .sulphide and 5% of other sulphur, compounds. If the vpartially purified gas is introduced through pipe` 74 to thelower portion/of the fuel bed below the support l26, itpasses upwardly through' the column of fuel together with steam formed through the injection of Water through pipe 48, and removes, as explained above, sulphur from the coke or fuel bed, substantiallyin accordance with the distribution ratio of sulphur between. the coke and gas heretofore explained and the sulphur compounds in the gas are'decomposed to form mainly hydrogen sulphide as heretofore explained.' If desired part of the purified gas may be introduced into the furnace through the pipe 7 4 and the other 'part of the gas introduced through the pipe 78. The gas which passes out ofthe shaft furnace throughthe pipe 52 is again washed and scrubbed-in the coolers and scrubbers.A

and finally passes into the oxide'purifiers 62 through the removal of the sulphur from .the coke.

The gas after being purified may be recirculated if desired to further reduce the sulphur content o f 'the coke in the. shaft furnace, or it may be retained in the gas holder 66, if the sulphur content of the gas has been reduced to vor below the legal standards and `distributed to consumers through' a pipe 86 or utilized in any manner desired.

In the preferred operation ofthe apparatus the volume of purified gas which is returned to the furnace is such that when this gas has been passed through the hot fuel bed and mixed with new gas being made, the sulphur contents of the gasmixture and the coke will be below the maximum sulphur content permissible. In this way the sul- -phur content of all of the gas passing through the purifier will be below the maximum sulphur content permissible.

While the operation of the process has been described and explained in connection ivith a Doherty shaft furnace, its application 1s by no means limited to this form of apparatus, and may be employed with advantage to other forms of gas producing apparatus.

Having thus described and explained the nature and objects of the invention, what is claimed as new is:

l. rlhe method of utilizing high sulphur coal fortlie production of metallurgical coke which 'comprises distilling the coal by direct heat tansfer' with a hot low B. t. u. gas so as to produce a rich gas having a high sulphur content and coke, burning a portion of the hot coke thus produced and passing the hot gaseous products of the combustion through the remaining coke so as to raise its temperature to incandescence, contacting steam with said incandescent coke to generate the low B. t. u. gas heating medium, purifying the enriched gas by removing h drogen sul hide therefrom, and returning tfie purifie gas into direct contact with the incandescent coke remaining to decompose the other sulphur compounds remaining in the galsI and to reduce the -sulphur content of the co e.

2. The method of utilizing hi h sulphur coal in the production of combusti le gas and metallurgical coke which comprises distilling said coal so as to evolve gas and produce colte, burning a portion of the said coke to raise the temperature of the remaining coke to vincandescence, purifying the said gas to remove hydrogen sul hide therefrom, and returning the purifie gas through the incandescent coke to remove sulphur compounds from the incandescent coke and to decompose the other sulphur compounds present in the gas. y .l

3. The method of utilizing high sulphur coal in the production of low sulphur gas which comprises distilling the coal so as to ,evolve gas and produce coke, removing hydrogen sulphide from the gas thus produced, thereafter passing the gas through the coke product of distillation at an incandescent temperature to decompose other sulphur cornpounds in the gas, and finally removing from the gas the hydrogen sulphide resulting from the decomposition of said other sulphur compounds.

l. The method of utilizing high sulphur carbonaceous fuel in the product-ion of lou1 sulphur gas which comprises distillingthe fuel so as to evolve gas and produce a 'car bonaceous residue, removing hydrogen sulphide from the gas thus produced, thereafter passing the gas through a bed of fuel at an incandescent temperature to decompose other sulphuncompounds remaining in the gas, and finally removing from the gas the hydrogen sulphide resultin from the decompo-` sition of said other sulp ur compounds.

5. The method of utilizin solid carbonaceous fuel havin` a high su phur content in makin combusti le gas of low sulphur content W ich comprises passing the fuel in a column through a shaft furnace, maintaining G. The method of utilizing solid carbo-` o the said gas by removal of hydrogen r naceous fuel having a high sulphur content in making combustible gas of low sulphur content which comprises passing the fuel through a shaft furnace in a column at a rate such that some unburned fuel will be discharged from the base of the column, maintaining a high temperature zone at an intermediate portion of the column by intermittently blasting air therethrough, applying rater to the fuelin the lower portion of the column between periods of air blasting to quench the fuel and generate steam passing the thus formed steam into the hi perature zone to generate gas, purifying the said gas by removal of hydrogen sulphide therefrom, returning the thus purified gas to the shaft and passing upwardly through the fuel column together with the said steam, and again purifying the gas leaving the fuel column.

7. The method of utilizing solid carbonaceous fuel having a high sulfur content in making combustible gas of low sulfur content ivhich comprises passing the fuel in a column through a furnace, igniting a midportion only of the fuel in the column, blasting air through said mid-portion to develop a high temperature' therein, burning the exhaust products of said blasting operation to 'furnish heat for generating steam, passing the generated steam through the said fuel column to forni water gas, purifying the said gas by removing hydrogen sulphide therefrom, 'and returning the purilied gas through thc said fuel column to remove undesirable constituents from the said fuel und to reduce the remaining impurities in A the said gas to a form easilyrcmoved in gas purifiers;

8. -The method of utilizing a solid carbonaceous fuel having high sulphur content in making lovv sulphur gas which comprises blasting air through a column ofthe fuel in an ignited condition t raise the temperature of a portion thereof to incandescence,

thereafter passing.` steam 'through the incandescent fuel to generate 'Water gas, removing tar and ammonia from the thereafter .'rtemoving hydrogen sulphide i from the gasglcirculating the so puried gas relationship therethroughg'v burning* through the l.incandescent fuel to remove impurities therefrom and to reduce .the remaining' impuritiesin the said gastoaform easily removed inj-gas puriers, and returning the gas through purifiers to reducjts sulphur content .beloof an allowable 1i1nit;--

. 9.' The method offutilizing: high sulphur coal in the' manufactureroff-fmetallurgical coke which'comprisesY'distilling gas and producingcoke from theco'al'gby passing a vhot low B. t. u.. gas in'pdirectfheat transferring 2? P01" tion of the coke product` ovf, .1s`a1d* distillatio-n so as to raise the temperature ofthe 'remaining coke to incandescence, 'purifying .the gas product of distillation so as to re- A gas so generated,

move hydrogen sul hide therefrom, and returning a portion o the purified gas through the incandescent zone of the chargeto reduce the sulphur content of the unbu/rned coke below an allowable limit.

10. The method of utilizing high sulphur coal to produce combustible gasl of low sulphur content which comprises distilling gas and producing coke from the coal by pass-- ing a hot low Byt. u. `gas in direct heat' phur content of the gas below an allowable limit. A In testimony 'whereof aix my signature.

'ROBE air G; eRIsWoLDL 

